1. Field of Invention
This invention relates to a vehicular safety warning system, more specifically, one capable of displaying both forward deceleration rate and full stop information automatically.
2. Description of Prior Art
Heretofore, deceleration indicating systems have been configured using incomplete information formats generated by compromised electrical circuitry. Traditionally, vehicles have been equipped simply with rear mounted red indicators illuminated in response to brake pedal actuation. Over time, inventors have recognized a need to enhance this abbreviated deceleration indicating convention. Earlier improvements have not been generally successful due to inherent limitations, such as:
(a) Many earlier arrangements were limited from the outset by suggesting inappropriate origination of the required speed reference signal. For example, Miller U.S. Pat. No. 4,751,493 (1988) and Perkins U.S. Pat. No. 4,730,181 (1988) suggest deceleration sensing by merely providing an on/off switch for the accelerator pedal. Some suggest a sensing connection to the engine, as in Zalar et al. U.S. Pat. No. 4,097,842 (1978) and Chen U.S. Pat. No. 4,772,868 (1988). It is not necessary nor desirable to announce every closure of the engine throttle. It is only important to show the vehicle is beginning to slow significantly. Another method suggests a weighted pendulum for g-force detection. A mechanical pendulum possesses questionable traits with respect to inclines, sensitivity and dampening. Yoshino U.S. Pat. No. 4,107,647 (1978) shows this sensing arrangement. Since these various methods aren't directly associated with a vehicle wheel, they can't be precisely related to vehicle speed as they should be.
(b) Other systems, desiring to obtain a reference signal more closely related to vehicle speed, suggest a rotating shaft or wheel associated with the drive-train act as part of a generator to produce a reference voltage. The amplitude of the voltage is thereby directly related to vehicle speed. For example, Ando U.S. Pat. No. 3,564,532 (1971) suggests this method. While technically more appropriate, this arrangement is none the less dependent upon generating a specific range of operating voltage from all transducer installations. Therefore, this method is inherently sensitive to transducer properties and individual installation peculiarities.
(c) Some prior art suggests speed sensing means be physically connected to the vehicle speedometer. This is not a practical method since provision for such attachment is generally not available on existing vehicles. For example, Thurman U.S. Pat. No. 4,594,574 (1986) suggests this difficult speedometer attachment requirement.
(d) Once initially detecting deceleration, most prior art simply energizes a signal in a preprogrammed manner, neglecting the opportunity to communicate specific real-time deceleration rate information via the indicator. For example, Van Ostrom U.S. Pat. No. 3,794,972 (1974) suggests this shortcoming.
(e) Some prior art suggests continuously signaling a warning at all times during low speed vehicle operation is desirable. Abel, et al. U.S. Pat. No. 4,841,276 (1989), for example, demonstrates this concept. Such signaling will likely help gain the attention of motorists approaching from the rear. However, prolonged signaling is likely to create a degree of annoyance for the motorist if he is then trapped in bumper-to-bumper, stop-and-go traffic. He then prefers to know only when the brake of the lead vehicle is applied.